JP2674662B2 - Semiconductor wafer grinding machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer grinding apparatus that grinds a semiconductor wafer as a work material while cooling the semiconductor wafer by introducing a cooling liquid into a grinding surface of a grinding wheel.

[Conventional technology]

Conventionally, in this type of grinding apparatus, when cooling a semiconductor wafer as a work material, a disposable method is generally used in which a constant amount of cooling liquid is simply kept flowing.

[Problems to be solved by the invention]

By the way, during the grinding process of a semiconductor wafer, it is known that the cause of the structural deformation generated in the semiconductor wafer, grinding baking, residual grinding stress or residual stress, etc. is brought by the grinding heat generated by the grinding, It is also empirically well known that the grinding heat rapidly rises when a grinding abnormality occurs. From this, it has become necessary to systematize the relationship between the grinding temperature and the occurrence frequency of defective products in order to eliminate the above-mentioned problems or to detect grinding abnormalities.

It is also possible to measure the grinding temperature, which is the basis for such a request, by abutting a thermocouple on the semiconductor wafer or by implanting a thermocouple in the grinding wheel, but the semiconductor wafer itself is thin and fragile material. Moreover, since the semiconductor wafer is usually ground while being rotated, it is very difficult to bring the thermocouple into contact with the semiconductor wafer. Further, even if a thermocouple is implanted in the grinding wheel, the grinding temperature of the semiconductor wafer is indirectly measured, and there is a problem that the grinding temperature cannot be accurately measured.

The present invention focuses on the fact that the grinding temperature can be obtained from the amount of heat obtained by the cooling liquid, and a semiconductor that can easily obtain the grinding temperature by circulating the cooling liquid and without processing or stressing the semiconductor wafer can be obtained. An object of the present invention is to provide a wafer grinding device.

[Means for solving the problem]

The present invention, in order to achieve the above objects, in grinding, in a semiconductor wafer grinding apparatus for cooling a semiconductor wafer as a work material by introducing a cooling liquid into the grinding surface of the grinding wheel, provided in the vicinity of the grinding surface of the semiconductor wafer A circulation flow path is provided to directly connect a discharge port of the cooling liquid for introducing the cooling liquid to the grinding surface and a discharge port for collecting the cooling liquid absorbing the grinding heat,
It is characterized in that a temperature measuring means for measuring the temperature of the cooling liquid which has become steady is provided in the middle of the circulation flow path.

[Action]

When the cooling liquid is circulated by providing the circulation passage, the cooling liquid absorbs the grinding heat generated in the grinding device and flows in the circulation passage. By circulating the cooling liquid, which has been conventionally discarded, it is possible to configure a grinding device that can always obtain the grinding temperature of the semiconductor wafer through the cooling liquid, and further to face the inside of the circulation flow passage in the middle thereof. If the temperature of the cooling liquid is measured by interposing a temperature measuring means, the grinding temperature of the semiconductor wafer can be obtained by the heat loss of the circulation passage obtained by the measured temperature, and this grinding temperature, or simply by the temperature measuring means, is measured. It is possible to systematize the correlation between the temperature and the occurrence frequency of defective products.

〔Example〕

A case where the present invention is applied to a grinding device for grinding a semiconductor wafer to a predetermined thickness before the dicing step will be described.

As shown in FIG. 1, a semiconductor wafer W grinding apparatus 1
Is provided with a stage 2 on which a semiconductor wafer W is placed and a grinding wheel 3 for grinding the semiconductor wafer W above the stage 2. The stage 2 is a semiconductor device driven by a drive device (not shown) connected to a rotation shaft 4. The wafer W is rotated with the wafer W placed thereon, and the grinding wheel 3 is moved up and down while being rotated by a drive device (not shown) connected to the drive shaft 5. With this configuration, the semiconductor wafer W is slowly rotated by itself during grinding, and the 00 surface, which is the surface thereof, is uniformly ground to a predetermined thickness by the grinding wheel 3 that is gradually lowered while rotating.

On the other hand, in order to eliminate the thermal influence of the semiconductor wafer W due to the grinding, the grinding heat generated by the grinding is applied to the semiconductor wafer W.
It is removed by the cooling liquid introduced into the grinding surface S composed of the grinding wheel 3 and the grinding wheel 3.

The cooling liquid is introduced into the grinding surface S from the discharge port 6 on the inflow side,
The grinding surface S absorbs the grinding heat and is discharged from the drain port 7 on the outflow side. The discharge port 6 and the discharge port 7 are communicated with each other by a circulation flow path 8, and a thermometer 9 which is a temperature detection means, a filter 10 and a circulation pump 11 are provided in the middle of the circulation flow path 8. . As a result, the cooling liquid is pressure-fed in the circulation passage 8 by the circulation pump 11, introduced into the grinding surface S from the discharge port 6 to cool the semiconductor wafer W, and sucked into the circulation passage 8 from the discharge port 7. The temperature of the liquid is measured by the thermometer 9, and finally the particulate matter ground by the filter 10 is removed, and the flow returns to the circulation pump 11. In addition, a replenishment liquid pipe 12 is connected between the filter 10 and the circulation pump 11 in the circulation flow path 8 to replenish the cooling liquid as appropriate.

The temperature of the cooling liquid measured by the thermometer 9 gradually rises from the start of grinding and reaches a steady temperature after a certain period of time. Therefore, in brief, when the temperature rises due to the relationship between the temperature indicated by the thermometer 9 in the steady state and the frequency of occurrence of defective semiconductor wafers W, or due to abnormal grinding or the like, the steady state is destroyed. And the frequency of occurrence of defective products can be numerically obtained.

Further, in this steady state, the following relationships are basically established.

Grinding heat = amount of heat released to the outside of the system That is, the temperature of the cooling liquid becomes constant,
The heat absorption and the heat dissipation are in balance. The heat absorption factor in this case is grinding heat, and the heat radiation factor is mainly heat released from the circulation flow path 8 itself to the atmosphere. Therefore,
If the amount of heat released into the atmosphere from the circulation passage 8 itself, which is considered to be the amount of heat released to the outside of the system, can be calculated, the grinding heat can be obtained, and in relation to the flow rate of the cooling liquid flowing through the circulation passage 8. The grinding temperature can be determined. The amount of heat released from the circulation passage 8 itself to the atmosphere is determined by the flow velocity of the cooling liquid, the heat transfer coefficient of the circulation passage 8, the contact area between the cooling liquid and the circulation passage, and the cooling measured by the thermometer 9. It can be calculated by the temperature difference between the liquid temperature and the atmospheric temperature.

In this way, if the grinding temperature is known, the relationship between the grinding temperature and the occurrence frequency of defective products such as warpage due to grinding cracks and residual stress of the semiconductor wafer W can be obtained.

〔The invention's effect〕

As described above, according to the present invention, it is possible to measure the grinding temperature by circulating the cooling liquid, and if the temperature of the cooling liquid is measured by the temperature detecting means, the grinding temperature that can be calculated from this measured value, or It is possible to systematize the relationship between the measured value and the occurrence frequency of defective products, and to reduce the occurrence frequency of defective products based on the systematized data.

[Brief description of the drawings]

FIG. 1 is a schematic view of a semiconductor wafer grinding apparatus embodying the present invention. 1 ... Grinding device, 2 ... Stage, 3 ... Grinding wheel, 6
…… Discharge port, 7 …… Discharge port, 8 …… Circulating flow path, 9 …… Temperature meter.

Claims (1)

(57) [Claims] 1. A grinding apparatus for a semiconductor wafer, wherein a cooling liquid is introduced into a grinding surface of a grinding wheel to cool a semiconductor wafer as a work material during grinding, which is provided near the grinding surface of the semiconductor wafer and is cooled to the grinding surface. A circulation flow path is provided to directly connect the discharge port of the coolant for introducing the liquid and the discharge port for collecting the coolant that has absorbed the grinding heat, and the temperature of the coolant becomes steady in the middle of the circulation flow path. An apparatus for grinding a semiconductor wafer, wherein a temperature measuring means for measuring the temperature is provided.